An awareness of the risks of sleep disorders in recent years has prompted a number of advances associated with sleep apnea and snoring. Sleep apnea is a known factor associated with heart problems.
Sleep apnea is generally regarded as an interruption in the breathing pattern of a sleeping subject. Interruptions of a breathing pattern may be spontaneous or may result from a breathing obstruction such as a sleeping subject's tongue blocking the airway or from partial or complete upper airway occlusion where the upper airway collapses, particularly under the reduced pressure generated by inhalation. Obstructive sleep apnea may result in lowered arterial blood oxygen levels and poor quality of sleep.
It is estimated that there are more than 40 million chronic snorers in the United States. Snoring is often a factor associated with sleep apnea. In addition to heart problems, sleeping disorders degrade the quality of rest for a person with the sleeping disorder as well as other people, such as a spouse, sharing the sleeping quarters.
Prior art efforts to provide data relative to sleep disorders have included the Sleep Apnea Monitor of U.S. Pat. No. 4,802,485. U.S. Pat. No. 4,804,485 provides a method of monitoring for sleep apnea that includes a number of sensors (blood-oxygen sensor, snoring sensor and head position sensor) mounted to headgear of a monitored subject. The sensors are, in turn, interconnected with a data logger for recording and subsequent analysis by a doctor or technician.
Other patents, such as U.S. Pat. No. 4,982,738, have included additional sensors for recording the time intervals between snoring events. Such advances have improved the content of the data recorded for later analysis by trained personnel.
Another advance, such as U.S. Pat. No. 5,275,159, have used a computer in conjunction with a data logger to improve the presentation of recorded data. The data logged under the invention of U.S. Pat. No. 5,274,159 could be presented under any of three possible formats: (1) as a graph of sensor value versus time; (2) as histograms and tables; and (3) as episodes per hour of a selected parameter.
While the prior art has offered a number of improvements in the technology associated with presenting recorded data, the final diagnosis of the source of the sleep disorder still lies with the attending physician.
The most common surgical procedure used by physicians for correcting sleep disorders such as apnea or snoring is uvulopalatopharnygoplasty ("UPPP"). Other procedures often used include adenoidectomy, tonsillectomy, septoplasty, turbinectomy, and polypectomy. In some cases physicians even perform surgery of the hypopharynx and tongue.
In the case of snoring, if the generation site of the snoring is below the plane of the uvula, then surgery becomes very complicated and, often, impractical. Also, although there is no definitive method for identifying sources of snoring, statistics show that UPPP reduces apnea 50% of the time and snoring 75-80% of the time. Because of the importance of the proper diagnosis of sleep disorders, a need exists for a simple and convenient method of determining the sources and types of sleep disorders that is not completely dependent upon the judgment and experience of an attending physician. It would be further advantageous to be able to easily identify the source of snoring to permit evaluation of the probability of success of the various surgical options.
Further, because of the risks associated with breathing obstructions, a need exists for a method of generating in index of breathing difficulty. Such index should transcend the known categories of symptoms to give a physician an indication of the types of risks associated with the level of breathing difficulty (e.g., heart problems, stroke, etc.)